Fan



I Sept. J'C. HOSCH 7 FAN Filed Jan. 15. 1927v 1 ME rme/ J CLAUDE #056 A fToe/VEY Patented Sept. 13, 1927.

"UNITED .MSTATE 3; on ons absent. or nos A GELEs, ma m ran.

Application filed January 15, 1927. Serial No. 161,375.

This invention relates to fans, and especially to fans oflarge size useful in ventilating systems, such as in theaters, halls, or the like. In such systems, it is sometimes desirable to provide an exhaut or discharge opening for the fan that departs considerably from circular form; for example, square openings are quite common. This is advantageous to facilitate the provision of such openings in the walls of buildings, and is also useful for simplifying the structure of the fan. It is evident that the flow of air out of such square exhaust openings is apt ls'to be uneven, being faster near the center and slower near the corners. It is one of the objects of my invention to correct th s condition, and to ensure a substantially uniform fiow, thereby increasing the volume or rate of air delivered by the fan.

I accomplish this result by appropriate formation of the fan blades. It is accordingly another object of my invention to provide a fan blade structure that is adapted to provide a strong movement of air beyond the blade ends.

My invention possesses many other advan-' tages, and has other objects which may be made more easily apparent from a consideration of one embodiment of my invention.

For this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to describe this form in detail 5 which illustrates the general principles 0 my invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of my invention is best defined by the appended claims. 7

Referring to the drawings:

Figure 1 is a perspective view of a portion of a fan structure embodying my invention, taken from the intake side;

Fig. 2 is a side View of one of the fan blades;

Fig. 3 is a cross section of the fan blade taken along plane 33 of Fig. 1; and

Fig. l is a sectional view of the blade, so taken along plane 4-4 of Fig. 2.

The fan casing 11 is shown as having a circular frame 12 that forms the circular intake aperture, and a square frame 13 spaced from frame 11 and forming a square exhaust or outlet aperture. Connecting the two frames 12 and 13 and forming a conduit between them, is sheet metal casing 14, square at the exhaust side andround-at the intake side.

The fan shaft 15 is supported in stationary bearings 16 adjustably mounted in a metal frame-like support 17. This support is suspended by means of a series of radial arms 18 which are fastened to the frame 12. The shaft 16 carries a spider 19 to which the fan blades 20 are fastened in overlapping relation.

The blades 20 are concaved along a longitudinal axis, as shown most clearly in Fig. 3. As viewed in Fig. 1, the blades are arranged to rotate in a clockwise direction, and the advancing edge 21 is formed of a straight portion, defined by radial lines so as to give it a wedge-like form. The lagging edge 22 is also straight, but is formed of a strip bent up at an angle with the main body of the blade, and toward the direction of movement. The pitch of the blades can obviously be set at the proper value, dependent upon the conditions of operation. It has been found that such a blade structure serves to pass a large amount of air efficiently.

If no further precautions be taken, it would be found that air would not be delivered as fast at the corners of frame 13 as at other points thereof,'since the blades 20 obviously cannot reach the corners. I remedy this by making it possible for the air to slide off the fan blade tips and to be urged toward the corners. V complished by curving the tips of the fan blades backwardly, as indicated at 23, Figs. 2 and 4. These curved tips prevent the air from eddying around the tips as they pass across the corner portions of the outlet opening, but instead guide it outwardly through the corners. I find that by this simple expedient, a substantially uniform flow of air can be obtained from the entire discharge openin Furt ermore, my fan can be used to equalize the flow of air in a fan outlet opening that is in general larger than the inlet opening, whether the increase in area is due to a change in shape, as in the present instance, or merely a change in size.

I claim: 7

1. In a fan, a casing having a round inlet aperture and an outlet aperture that has an area materially greater than the inlet aperture, and a fan rotatable in the casing and This can be achaving blades- Wi-th a backwardly curved blade, a flange at the rear edge,, and a tip tip. having a backward tilt.

2. In a fan, a casing having a round inlet 4. In a fan, a casing having a round inlet aperture and a square outlet aperture, and a aperture and a square outlet aperture a se- 16 5 fan rotatable in the casing and having blades ries of radial overlapping fan blades formwith a backwardly curved tip to provide a ing a fan rotatable in the casing, said blades flow of air through the corners of the outlet each having a concave body portion, and a aperture. tip having a backward tilt.

3. A fan blade having a concave body por- In testimony whereof I have hereunto set 20 10 tion, a fiat edge connected to the body pormy hand; tion and forming the advancing: edge of the I r J. CLAUDE, osoH. 

